A corona charger is used to generate an electrostatic charge on a surface, for example, a sheet of paper, a photoconductor or a transport web. A corona charge typically includes one or more tightly strung corona wires. The two ends of each wire are firmly attached to the corona charger housing, for example, by copper lugs, or by manually twisted loops which are connected to the corona charger housing. Applying high voltage to these corona wires creates the requisite charge.
The corona wires are usually mounted one by one. Mounting and adjusting the tension of each wire independently of other wires is time consuming and relatively expensive. In the mounting process the wire is touched multiple times by tools or by the operator's hand. The mounting process includes unpacking the wire, mounting one end of each wire into the corona charger, attaching a tensioning spring to the other end of each wire, and mounting this other end of each wire and the tensioning spring into the corona charger housing.
U.S. Pat. Nos. 4,112,298, 4,258,258, 5,140,367, 5,181,069, 5,358,165, and 5,424,540 describe a corona charger that utilizes individual wires strung to produce separate corona wire strings. These patents do not disclose the process of assembling these wires. FIG. 1 illustrates an OCE charger, including a five string corona wire strung in a serpentine manner. The corona wire is mounted on four grooved sleds, each of which is tensioned by a spring.
The tension of each spring has to be properly adjusted. This requires that some or all of these springs be adjusted several times, making it time consuming and relatively expensive to properly tension the corona wire.
Furthermore, the usual way of mounting corona wires in a corona charger is difficult and time consuming because these wires are thin and are easily damaged by handling. Even small damage to the wires can cause breakage or non-uniformity in the charge generated. Finally, the wires need to be renewed regularly because of contamination damage.